It's difficult to say if your pup is truly aggressive, or needs a LOT more exercise. At that age, I tend to believe it is not aggression at all, just a puppy that isn't getting enough exercise.
Think along the line of your two boys. If I came over at 8:00 p.m., and gave them each a Red Bull and a bag full of chocolate minitures and told them "I want you to finish your Red Bull and your candy and then go to sleep." What do you think would happen?
Hondo Von Dopplet L Bauernhof "Hondo"- GSD
Lilie's Tug McGraw "Tug" - Golden Retriever
Maggie - Mini Dachshund (Rescue)
Lonestar Pivo - Texas Blue Lacy
Ashe - Barn Cat
Katie / APHA